1. Field of the Invention
Exemplary aspects of the present invention relate to a gloss application sheet and an image forming apparatus, and more particularly, to a gloss application sheet overlaid on a recording medium bearing a toner image, and an image forming apparatus using the gloss application sheet.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges a surface of an image carrier; an optical writer emits a light beam onto the charged surface of the image carrier to form an electrostatic latent image on the image carrier according to the image data; a development device supplies toner to the electrostatic latent image formed on the image carrier to make the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image carrier onto a recording medium or is indirectly transferred from the image carrier onto a recording medium via an intermediate transfer member; a cleaner then cleans the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image on the recording medium, thus forming the image on the recording medium.
In such fixing device, a heating roller and a pressing roller pressed against each other apply heat and pressure to a recording medium bearing an unfixed toner image as the heating roller and the pressing roller nip and convey the recording medium. Thus, the heat and the pressure fix the toner image on the recording medium. Specifically, the heating roller contacts the unfixed toner image on the recording medium to melt the toner. Accordingly, the melted toner, which contains resin to facilitate melting, may adhere to the surface of the heating roller. When the resin in the toner adhered to the heating roller solidifies, the solidified resin may generate asperities on the surface of the heating roller. Consequently, when the heating roller having such surface asperities contacts the unfixed toner image on the recording medium to fix the unfixed toner image, the surface asperities of the heating roller may generate asperities on the fixed toner image. As a result, the fixed toner image may not have the requisite gloss.
Further, when the recording medium bearing the melted toner image is separated from the heating roller, the surface of the toner image is roughened. Accordingly, the toner image may not have the requisite gloss.
To address those problems, a gloss application sheet may be overlaid on the image side of the recording medium which bears the unfixed toner image, so that the heating roller applies heat to the unfixed toner image on the recording medium via the gloss application sheet to melt the unfixed toner image. Thus, the smooth surface of the gloss application sheet flattens and smoothes the surface of the toner image. Thereafter, when the toner image is cooled and solidified, the gloss application sheet is separated from the recording medium. As a result, the toner image has a uniform gloss.
Use of such gloss application sheet involves heat being transmitted from the heating roller to the unfixed toner image on the recording medium via the gloss application sheet. Accordingly, the thinner the gloss application sheet the more effectively it transmits heat. However, a thinner gloss application sheet may have decreased rigidity, and therefore may be more easily wound around the heating roller. Consequently, the gloss application sheet may not be adhered to the recording medium properly, resulting in uneven gloss of the toner image fixed on the recording medium.